Conventionally, in electronic components such as liquid crystal display device, integrated circuit device, solid-state imaging device and organic EL, a photosensitive resin composition is generally used when forming a flattening film for imparting flatness to a surface of the electronic component, a protective film for preventing deterioration or damage of the electronic component, or an interlayer insulating film for keeping insulation. For example, in the production of a TFT liquid crystal display device, a backplate is fabricated by providing a polarizing plate on a glass substrate, forming a transparent electroconductive circuit layer such as ITO and a thin film transistor (TFT) thereon, and covering the transistor with an interlayer insulating film, a top plate is fabricated by providing a polarizing plate on a glass substrate, forming, if desired, patterns of a black matrix layer and a color filter layer, and further forming sequentially a transparent electroconductive circuit layer and an interlayer insulating film, and after disposing these two plates to oppose through a spacer, a liquid crystal is sealed in between the backplate and the top plate. In this process, the photosensitive resin composition used when forming the interlayer insulating film is required to be excellent in the sensitivity, residual film ratio, heat resistance, adhesion and transparency. Also, excellent aging stability during storage is required of the photosensitive resin composition.
As regards the photosensitive resin composition, for example, Patent Document 1 proposes a photosensitive resin composition containing (A) a resin soluble in an aqueous alkali solution, which is a polymer of (a) an unsaturated carboxylic acid or an unsaturated carboxylic anhydride, (b) an epoxy group-containing radical polymerizable compound and (c) another radical polymerizable compound, and (B) a radiation-sensitive acid-producing compound, and Patent Document 2 proposes a photosensitive resin composition containing an alkali-soluble acrylic polymer binder, a quinonediazide group-containing compound, a crosslinking agent and a photo-acid generator. However, both of these compositions are insufficient in terms of sensitivity, residual film ratio of the unexposed area, resolution and aging stability and are not enough for producing a high-quality liquid crystal display device. Patent Document 3 proposes a positive chemical amplification resist composition containing a crosslinking agent, an acid generator and a resin having a protective group capable of being cleaved by the action of an acid, where the resin itself is insoluble or sparingly soluble in an aqueous alkali solution but becomes soluble in an aqueous alkali solution after cleavage of the protective group. However, this composition is insufficient in terms of adhesion or transmittance and is not enough for producing a high-quality liquid crystal display device. Patent Document 4 proposes a radiation-sensitive resin composition containing an acid generator and a resin having an acetal structure and/or a ketal structure and an epoxy group, but this composition is low in the sensitivity and is not good.    Patent Document 1: JP-A-5-165214    Patent Document 2: JP-A-10-153854    Patent Document 3: JP-A-2004-4669    Patent Document 4: JP-A-2004-264623